How big a solar battery do I need to store all my home's electricity?

Seasonal Storage Thought Experiment

• Many commenters note the author’s premise—storing all summer surplus for winter use—highlights how extreme and impractical true seasonal storage is for homes.
• A 1 MWh–scale battery is technically possible in physical size but economically absurd for most households once cost, cycle life, and space are considered.
• Several argue you’d instead overbuild generation and size batteries for days or weeks, not months, then accept grid or generator backup for rare worst cases.

Solar vs Battery Sizing and Cost

• Panels are now often cheaper per added kWh than extra battery; for many, roof or yard area, not module price, is the limit.
• Diminishing returns: small batteries (5–15 kWh) plus a sensible array already cover most daily shifting and peak-rate avoidance; additional storage quickly delivers less incremental benefit.
• Some users share data: modest arrays plus 10–20 kWh storage can cover large fractions of annual use but still fall short in deep winter or long cloudy spells.

EVs, V2G, and Mobile Storage

• Several foresee EVs (≈60–100 kWh packs) as key household storage, via vehicle‑to‑load/grid.
• Others worry about added cycle wear and premature degradation; economics depend on battery lifespan and tariff spreads.

Fire, Safety, and Chemistries

• Concerns about large lithium packs as fire/explosion hazards; comparisons to stored propane, heating oil, diesel.
• Distinction made between volatile Li‑ion/po chemistries and more stable LFP, sodium‑ion, saltwater or sand‑based systems; placement in sheds or separate structures is common advice.
• Some note that fossil fuels carry their own risks (explosions, spills) but are socially normalized.

Grid, Community Storage, and Equity

• Strong disagreement on off‑grid futures: some are fully off‑grid and happy; others say most people prefer reliable grids and economies of scale.
• Worries that affluent households exiting or minimizing grid use push rising infrastructure costs onto poorer non‑solar users; countered by claims that tariffs and fixed fees can adapt.
• Community‑scale or substation‑scale storage is argued to be more efficient than every house owning huge batteries; the “grid as virtual seasonal storage” via net metering is emphasized where policies allow.

Alternatives and Design Tricks

• Alternatives discussed: generators (diesel, propane, gas), hydropower on streams, thermal/seasonal heat storage (sand, basalt, big hot‑water “thermoses”), hydrogen or synthetic fuels, gravity storage, but most are seen as niche or less economical than batteries today.
• Multiple anecdotes show that careful load reduction, passive house design, smart orientation (east/west panels), and modest batteries can achieve high (70–90%) self‑sufficiency without chasing full seasonal storage.